In textile fiber drafting apparatus in a spinning frame which includes plural sets of paired top and bottom drafting rollers along the corresponding plural number of spinning units of the spinning frame, a group of several bottom rollers, spaced from each other in each of the lines or rows of drafting rollers are mounted on a common shaft, thus constituting a series or a block of bottom rollers, and a plurality of such shafts or series of bottom rollers are connected together thereby to provide an integral structure of bottom drafting rollers for all the spinning units on either side of the spinning frame. The bottom rollers thus arranged in each line are usually driven directly by a driving mechanism disposed in the gear end frame on one end of the spinning machine.
Such conventional arrangement of bottom drafting rollers poses a problem in replacing parts in the drafting apparatus, in particular, the endless aprons or belts which are installed over the bottom rollers in a certain line for transferring fibers while guiding them properly. That is, though old aprons may be removed easily merely by cutting them off, new ones are installed by removing all the bottom rollers for one series from a roller stand, and then fitting the aprons over the rollers while moving them in longitudinal direction of the rollers, which is an extremely troublesome and time consuming operation. Furthermore, in the event of entanglement of fibers around the bottom rollers at their fiber passage portions, it will take much time and labor to remove such fibers therefrom. Since the fibers entangled on the rollers cannot be removed merely by moving them toward the end thereof, it is necessary to cut off the fibers or to disentangle them, which requires a considerable length of time. In addition, fiber lint or fly produced during the drafting and spinning operation and accumulated within the narrow spaces adjacent to the aprons is extremely difficult to remove. This is because the bottom rollers are connected together, forming an integral unit extending all the way along the length of the spinning units disposed on either side of the spinning frame and, therefore, the spaces where the fly is deposited are difficult of access by a fly removing means, due to the space available.
One possible solution for the problem is shown in U.S. Pat. No. 2,193,196 (Jackson) wherein separate roller stands are provided, each having a removable pair of bottom rollers. However, this requires an openable roller stand which also has removable top rollers and, thus, considerable roller adjustment is required when the roller stands are opened to remove the entangled fly. In addition, the roller arrangement permits rapid accumulation of fly so that the roller stands require frequent cleaning.
The problems of fly accumulation and removal have become more acute in view of recent developments in the art of spinning yarns. For example, because it is a very up-to-date process of spinning, a new type spinning machine, which produces a so-called fasciated yarn using a pneumatically-operated false-twist nozzle, has been attracting the interest of the relevant industry in recent years. It is a kind of fluid-jet spinning process which makes possible the production of yarn at a rate more than ten times than that turned out by the conventional ring spinning process. Accordingly, this new spinning process calls for a high draft and, therefore, its drafting apparatus tends to be susceptible to the aforementioned problems which hamper the practical use of such fluid-jet spinning process. That is, its drafting apparatus which operates at an extremely high speed will cause its aprons to wear faster and, under the influence of the accompanying streams of air, the entanglement of fibers around the drafting rollers and the production of fly are more liable to take place during the drafting operation. Though provision may be made to minimize such entanglement of fibers and production of fly, it is highly desirable to provide effective means for facilitating removal of such fibers and fly, if they accumulated, and also to facilitate the replacement of aprons when required to do so.
The apparatus according to the present invention has been conceived with these considerations in mind. Therefore, it is an object of the present invention to provide a drafting apparatus by which removal of fibers entangled on the bottom rollers and fly accumulated adjacent to the aprons is made easier and the necessary replacement from time to time of the endless aprons is greatly facilitated.
It is another object of the invention to provide a drafting apparatus in which the roller driving mechanism is protected against the in ingress of fly thereinto.
It is still another object of the invention to provide a drafting apparatus by which more accurate, drafting, bottom rollers may be manufactured with ease.